Abstract: Since low resistivity oil reservoirs and high resistivity water reservoirs are present in Putaohua formation of southern Golong area, oil-water formation recognition is difficult. To solve the problem, the genesis of low resistivity oil reservoirs is made clear first. Therefore, typical low resistivity oil reservoir and conventional oil reservoir core samples are taken, and Petrophysical analysis, Particle size analysis, Mercury-injection, NMR and X-diffraction experiments are done for them. The difference in lithology, petrophysics, pore structure, clay minerals, formation water salinity etc. between low resistivity oil reservoirs and conventional oil reservoirs is found out by comparison. It pointed out low resistivity of oil zones in Putaohua formation of southern Golong area is mainly caused by there factors: fine-grained lithology, high shale content; high clay-excess conductivity; more microscopic cappillary pore, high irreducible water saturation. The result will provide theoretical basis for identification and interpretation of low resistivity oil reservoirs in Putaohua formation of southern Golong area.